Through-plane Proton Conductivity Research Articles

Double cross-linked 3D layered PBI proton exchange membranes for stable fuel cell performance above 200 °C

Phosphoric acid doped proton exchange membranes often experience performance degradation above 200 °C due to membrane creeping and phosphoric acid evaporation, migration, dehydration, and condensation. To address these issues, here we present gel-state polybenzimidazole membranes with double cross-linked three-dimensional layered structures via a polyphosphoric acid sol-gel process, enabling stable operation above 200 °C. These membranes, featuring proton-conducting cross-linking phosphate bridges and branched polybenzimidazole networks, effectively anchor and retain phosphoric acid molecules, prevent 96% of its dehydration and condensation, improve creep resistance, and maintain excellent proton conductivity stability. The resulting membrane, with superior through-plane proton conductivity of 0.348 S cm−1, delivers outstanding peak power densities ranging from 1.20–1.48 W cm−2 in fuel cells operated at 200-240 °C and a low voltage decay rate of only 0.27 mV h−1 over a 250-hour period at 220 °C, opening up possibilities for their direct integration with methanol steam reforming systems.

Construction of Successive Proton Conduction Channels to Accelerate the Proton Conduction Process in Flexible Proton Exchange Membranes.

Successive proton conduction channels are constructed with the spin coating method in flexible proton exchange membranes (PEMs). In this research, phosphoric acid (PA) molecules are immobilized in the multilayered microstructure of Kevlar nanofibers and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) polymer molecular chains. As a result, successive proton conduction channels can accelerate the proton conduction process in the prepared membrane with the multilayered microstructure. Additionally, the microstructure fractures of the composite membranes from the external force of folding and stretching operations are modified by the inner PA molecules. Notably, numerous PA molecules are further combined through formed intermolecular hydrogen bonding. The stretched membrane absorbs more PA molecules owing to the arrangement of PA molecules, Kevlar nanofibers, and SEBS molecular chains. The stretched membrane thus exhibits the enhanced proton conduction ability, such as the through-plane proton conductivity of 1.81 × 10-1 S cm-1 at 160 °C and that of 4.53 × 10-2 S cm-1 at 120 °C lasting for 600 h. Furthermore, the tensile stress of PA-doped stretched membranes reaches (3.91 ± 0.40)-(6.15 ± 0.43) MPa. A single proton exchange membrane fuel cell exhibits a peak power density of 483.3 mW cm-2 at 120 °C.

Magnetically aligned composite membranes based on sulfonated poly(ether ether ketone) and phosphotungstic acid-loaded magnetic nanoparticles for fuel cell

In this work, phosphotungstic acid (HPW)-loaded polydopamine-coated magnetic nanoparticles (DMNPs@HPW) were prepared and incorporated into sulfonated poly(ether ether ketone) (SPEEK) matrix with magnetic field assistance to construct aligned channels to shorten proton transport pathways. The structure of the prepared composite membranes (M-SP/DMNPs@HPW) with magnetic field-induced proton channels was confirmed by SEM. The proton conductivity of M-SP/DMNPs@HPW-2 was significantly improved, with in-plane proton conductivity (σ//) of 159.3 mS/cm and through-plane proton conductivity (σ⊥) of 129.2 mS/cm in the hydrated state at 80 °C, which were 1.31 and 1.57 times higher than the pristine SPEEK membrane, due to the strong acidity of HPW and acid-base interaction of amine and sulfonic acid groups. Meanwhile, the σ⊥ of M-SP/DMNPs@HPW-2 was 1.14 times higher than that of SP/DMNPs@HPW-2 membrane prepared without magnetic field assistance. The fuel cell power output of M-SP/DMNPs@HPW-2 was 433 mW/cm2, while SP/DMNPs@HPW-2 and pristine SPEEK membranes tested under the same conditions were 360 mW/cm2 and 277 mW/cm2, respectively. The hydrogen crossover of M-SP/DMNPs@HPW-2 was slightly increased compared to SP/DMNPs@HPW-2 due to the construction of through-plane proton transport channels in the membrane.

Electrospinning-assisted construction of rapid proton conduction channels in halloysite nanotube-encapsulated ionic liquid-embedded sulfonated poly(ether ether ketone) proton exchange membranes

The most fatal drawback of traditional sulfonated polymer proton-exchange membranes (PEMs) is their heavy dependence on water molecules to conduct protons, which causes a sharp decrease in their proton conductivity in low-humidity environments. Here, composite membranes were fabricated by electrostatically spinning halloysite nanotube-encapsulated ionic-liquids (IL@HNTs) incorporated into sulfonated poly(ether ether ketone) (SPEEK) (SPEEK/IL@HNTs). Using electrospinning, one-dimensional IL@HNTs ionogels with good water absorption were axially and uniformly aligned along the fiber filament direction. This formed long-range uninterrupted proton conduction pathways that greatly improved the proton conductivity of the composite membrane under various humidity environments. The axially-aligned structure facilitated crystallization, which improved the mechanical properties and thermal stability of the composite membrane. The SPEEK/6IL@HNTs membrane exhibited a through-plane proton conductivity of 139.2 mS cm−1 at 90 °C/98 % RH, representing a significant increase compared with the intrinsic SPEEK membrane. The SPEEK/6IL@HNTs membrane demonstrated a maximum power density of 732 mW cm−2, which exceeded that of the Nafion115 membrane (328 mW cm−2) by a factor of 2.2. It exhibited a single-cell performance equivalent to that of the Nafion212 membrane (723 mW cm−2), demonstrating that this provides a feasible approach to operating fuel cells in low-humidity environments without additional humidification.

Scanning electrochemical microscopy for the differentiation of radical-induced degradation mechanisms in polymer electrolyte membranes.

In this work, a spatially resolved analytical method based on scanning electrochemical microscopy (SECM) to distinguish different degradation phenomena in polymer electrolyte membranes was developed. SECM was combined with a Franz diffusion cell to distinguish between radical-induced aging of a sulfonated tetrafluoroethylene based fluoropolymer-copolymer due to deactivation of the sulfonic acid groups followed by a decreased proton conductivity, and the radical-induced formation of cracks and holes in the polymer. The experiments were performed with ferrocyanide as redox mediator to detect holes and cracks, and protons (sulfuric acid) to determine the through-plane proton conductivity, respectively. A pristine Nafion™ membrane, a pristine Nafion™ membrane with an artificial pinhole and a Nafion™ membrane aged with Fenton's reagent were investigated to prove the measurement principle. It could be shown that holes and cracks can be reliably detected with this approach and discriminated from a change in proton conductivity. The presence of holes in the investigated aged membranes was confirmed by scanning electron microscopy, whereas the loss of sulfonate groups could be supported by infrared spectroscopy measurements.

Polyethyleneimine-confined halloysite nanotubes for poly(2,5-benzimidazole) composite membranes with phosphoric acid retention and proton conductivity via ion pairs for wide-temperature PEMFCs

To prevent phosphoric acid (PA) from leaching and harming traditional polybenzimidazole-based proton exchange membranes, polyethyleneimine-confined halloysite nanotubes (PEI@HNTs) were embedded in poly (2,5-benzimidazole) membranes to construct rich ion pairs that stably conducted protons. With the aid of supercritical carbon dioxide, PEI oligomers with basic groups were confined in HNTs. Then, through in-situ synthesis, highly-dispersed PEI@HNT enhanced the mechanical stability of composite membranes, whose basicity improved the absorption and retention capacity of PA. The PEI@HNTs/ABPBI composite membrane exhibited excellent mechanical strength and electrical performance over a temperature range of 40–180 °C. The through-plane proton conductivity of the 5%PEI@HNTs/ABPBI composite membrane was 0.061 S cm−1 at 98% relative humidity and 90 °C and 0.049 S cm−1 under anhydrous conditions at 180 °C. This performance was attributed to strong hydrogen bonding between PEI and PA, as well as the excellent retention of bound water within the HNTs. The peak power density of PA-doped 5%PEI@HNTs/ABPBI composite membrane reached 0.235 W cm−2 and 0.418 W cm−2 at 120 °C and 180 °C under anhydrous conditions, respectively, which were 1.68 and 1.96 times higher than those obtained with the pristine PA-ABPBI membrane. These results highlight the potential of this composite membrane for applications requiring a wide temperature range.

Hydrocarbon-Based Composite Membrane Using LCP-Nonwoven Fabrics for Durable Proton Exchange Membrane Water Electrolysis.

A new hydrocarbon-based (HC) composite membrane was developed using liquid crystal polymer (LCP)-nonwoven fabrics for application in proton exchange membrane water electrolysis (PEMWE). A copolymer of sulfonated poly(arylene ether sulfone) with a sulfonation degree of 50 mol% (SPAES50) was utilized as an ionomer for the HC membranes and impregnated into the LCP-nonwoven fabrics without any surface treatment of the LCP. The physical interlocking structure between the SPAES50 and LCP-nonwoven fabrics was investigated, validating the outstanding mechanical properties and dimensional stability of the composite membrane in comparison to the pristine membrane. In addition, the through-plane proton conductivity of the composite membrane at 80 °C was only 15% lower than that of the pristine membrane because of the defect-free impregnation state, minimizing the decrease in the proton conductivity caused by the non-proton conductive LCP. During the electrochemical evaluation, the superior cell performance of the composite membrane was evident, with a current density of 5.41 A/cm2 at 1.9 V, compared to 4.65 A/cm2 for the pristine membrane, which can be attributed to the smaller membrane resistance of the composite membrane. From the results of the degradation rates, the prepared composite membrane also showed enhanced cell efficiency and durability during the PEMWE operations.

Spacer-Engineered Ionic Channels in Covalent Organic Framework Membranes toward Ultrafast Proton Transport.

Side-chain engineering of covalent organic frameworks as advanced ion conductors is a critical issue to be explored. Herein, ionic covalent organic framework membranes (iCOFMs) with spacer-engineered ionic channel are de novo designed and prepared. The ionic channels are decorated with side chains comprising spacers having different carbon chain lengths and the -SO3 H groups at the end. Attributed to the synergistic contribution from the spacers and the -SO3 H groups, the iCOFM with moderate-length spacer exhibit the highest through-plane proton conductivity of 889 mS cm-1 at 90°C.

Modification of sulfonated poly(arylene ether nitrile) proton exchange membranes by poly(ethylene-co-vinyl alcohol).

The modification of the physicochemical properties of sulfonated poly(arylene ether nitrile) (SPAEN) proton exchange membranes was demonstrated by poly(ethylene-co-vinyl alcohol) (EVOH) doping (named SPAEN-x%). By controlling the temperature during membrane preparation, the side reactions of the sulfonic acid groups to form sulfonic acid esters were effectively prevented, greatly reducing the proton conductivity of the membranes. Due to the flexible chain of EVOH, SPAEN-8% showed a relatively high elongation of 30.2%, which enhanced the aromatic polymers' flexibility. The SPAEN-2% membrane exhibited proton conductivity of 166, 55, and 9.6 mS cm-1 at 95%, 70%, and 50% relative humidity, respectively, higher than those of the other SPAEN-x% membranes and even comparable to that of Nafion 212. The water uptake, morphological study, and through-plane proton conductivity of the membranes were studied and discussed. The results suggest that EVOH doping can be used as an effective strategy to improve SPAEN-based proton exchange membranes' performance.

Charge transfer mechanisms in 40SiO2-40P2O5-20ZrO2 /sulfonated styrene-ethylene-butylene-styrene hybrid membranes for low temperature fuel cells

A series of hybrid membranes synthetized via sol-gel chemistry and direct infiltration method have been prepared, consisting of sulfonated styrene-ethylene-butylene-styrene block copolymer (sSEBS), as polymeric matrix, and a zirconia modified phosphosilicate (40SiO2–40P2O5–20ZrO2) as inorganic component. The infiltration procedure has been carried out by immersion of sSEBS membranes in a 40SiO2–40P2O5–20ZrO2 sol solution for 5, 10, 20, and 40 min. The hybrid infiltrated membranes (sSEBS-Zr) have been thermally characterized to further investigate their suitability as electrolytes for low temperature fuel cells. TGA thermograms showed that sSEBS-Zr were more thermally stable than sSEBS. DSC thermograms showed that the addition of inorganic component decreases the Tg of the polystyrene block in hybrid membranes sSEBS-Zr. DETA showed significant differences in the charge transfer mechanisms between low and high temperature regions. The through-plane proton conductivity analysis showed that the sSEBS-Zr infiltrated 10 min had a better proton conductive capacity at 333K, thus showing that longer infiltration times might induce excessive M-O-M′ bonds, causing competition for the available proton sites. These results indicated that the proposed methodology shows good agreement with experimental performance data in hydrogen PEMFCs. Nonetheless, when DMFCs are considered, minimizing the permeability of methanol enhances more the performance than increasing the proton conductivity.

How Electrochemical Impedance Spectroscopy Helps Drive Innovation in Fully Hydrocarbon, Reinforced Polymer Electrolyte Membranes

The realm of hydrocarbon-based polymer electrolyte membranes (PEMs) has undergone substantial changes over the past decade. A new era has emerged, based upon strong, fundamental R&D emphasizing both improved performance across a wider range of operating conditions, and greater combined chemical-mechanical stability, when integrated into a state-of-the-art fuel cell. The groundwork has been laid for commercialization of highly promising, fluorine-free technologies which simultaneously outperform previous generation materials, and address weaknesses historically attributed to all hydrocarbon-based membranes. Hydrocarbons address critical issues with perfluorinated sulfonic acid (PFSA) materials. Reduced gas crossover allows longer component lifetimes, operational window for system pressures, and reduced hydrogen venting. Higher temperature tolerances allow system operation or excursions to ≥ 100 °C, which affords a myriad of potential benefits such as reduction in heat exchanger volume, improved system water management, and increased catalyst activity due to mitigated activation losses. Furthermore, higher operating temperatures go hand-in-hand with greater pollution tolerance, and hence reduced hydrogen purity requirements.The award-winning hydrocarbon-based PEM, Pemion®, produced by Ionomr Innovations, is nested at the center of these exciting developments. Mechanically reinforced composite membranes are produced at scale utilizing advanced roll-to-roll manufacturing techniques, affording a hydrocarbon-based PEM that, for the first time, exhibits performance parallel to or greater than incumbent perfluorinated sulfonic acid (PFSA)-based PEMs. These developments, however, would not be possible without powerful characterization methods such as electrochemical impedance spectroscopy (EIS). Assessments of a membrane’s in-plane and through-plane proton conductivity are used to derive valuable insight to its constituents, the ion-conducting ionomer and chemically-inert mechanical reinforcement, as well as their interrelation. The anisotropic nature of the composite membranes is probed via comparison of in-plane and through-plane conductivity. The sensitivity of through-plane conductivity measurements to experimental parameters such as cell pressure are probed, and a new cell design is realized to reduce measurement error. These data help identify favorable and unfavorable material processing and manufacturing techniques, and their implications to in-situ fuel cell performance. The net consequence of these findings is establishing EIS as a core component of an iterative material design and production process for output of consistent, high-performance PEMs.

High-performance fuel cells using Nafion composite membranes with alignment of sulfonated graphene oxides induced by a strong magnetic field

Proton exchange membrane (PEM) is a key component of proton exchange membrane fuel cells (PEMFCs) and provides proton conduction between fuel and oxidant, and it is vitally important and practical to develop PEMs with high proton conductivity through membranes. However, it is still a major challenge to develop such membranes with high through-plane proton conductivity. In this study, Nafion composite membranes with sulfonated graphene oxides (SGOs) were prepared from self-assembly sol-gel either in or not in a strong magnetic field. Microstructures, water uptake, and proton conductivity of the SGO/Nafion composite membranes have been investigated extensively. For the SGO/Nafion composite membranes recast without a magnetic field, it is found that the water uptake and in-plane proton conductivity are greatly increased with the increasing SGO content. Interestingly, SGO/Nafion composite membranes with a low SGO content of ∼ 0.5 wt% exhibit lower crystallinity and higher in-plane proton conductivity. For the SGO/Nafion composite membranes recast in a strong through-plane magnetic field, it is very appealing to find their through-plane proton conductivity is significantly higher than that of the composite membranes recast without a magnetic field. This is attributed to that the protons transport in the membranes preferentially along the water channels primarily interconnected by the aligned SGOs through-plane induced by the strong magnetic field, as confirmed by SEM. Applied in a single PEMFC, the resultant SGO/Nafion composite membrane with 1 wt% SGOs, recast in a strong magnetic field of 1.5 T, demonstrates a high power-density of 1.056 W cm-2, which is far superior to those of pristine Nafion and SGO/Nafion composite membranes recast without a magnetic field. The study provides a novel strategy for preparing proton exchanging membranes with high performances for new-generation fuel cells.

Dielectric Properties in Oriented and Unoriented Membranes Based on Poly(Epichlorohydrin-co-Ethylene Oxide) Copolymers: Part III.

The dielectric spectra and conductivity properties of neat poly(epichlorohydrin-co-ethylene oxide)(PECH-co-EO) copolymer and two modified copolymers with a 20% or 40% of dendron 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy] benzoate units were analysed. A process of thermal orientation was applied to the copolymers to fine-tune the molecular motion of the side chains and determine their validity for cation transport materials. The study was conducted using Dielectric Thermal Analysis (DETA). The spectra of the modified unoriented and oriented copolymers consisted of five dielectric relaxations (δ, γ, β, αTg, and αmelting). The analysis of the relaxations processes shows that as the grafting with the dendron units increases, both the lateral and main chains have a greater difficulty moving. The thermal orientation induces in the main chain partial crystallization, including the polyether segments, and modifies the cooperative motion of the main chain associated with the glass transition (αTg). A deep analysis of the electrical loss modulus revealed that the degree of modification only modifies the temperature peak of each relaxation, and this effect is more perceived if the dendron unit content is higher (40%). The thermal orientation process seems equal to the spectra of CP20-O and CP40-O to the point that the degree of modification does not matter. Nevertheless, the fragility index denotes the differences in the molecular motion between both copolymers (40% and 20%) due to the thermal orientation. The study of the electric conductivity showed that the ideal long-range pathways were being altered by neither the thermal orientation process nor the addition of dendrimers. The analysis of the through-plane proton conductivity confirmed that the oriented copolymer with the highest concentration of dendrimers was the best performer and the most suitable copolymer for proton transport materials.

A Near-Isotropic Proton-Conducting Porous Graphene Oxide Membrane.

A graphene oxide (GO) membrane is an ideal separator for multiple applications due to its morphology, selectivity, controllable oxidation, and high aspect ratio of the 2D nanosheet. However, the anisotropic ion conducting nature caused by its morphology is not favorable toward through-plane conductivity, which is vital for solid-state electrolytes in electrochemical devices. Here, we present a strategy to selectively enhance the through-plane proton conductivity of a GO membrane by reducing its degree of anisotropy with pore formation on the nanosheets through the sonication-assisted Fenton reaction. The obtained porous GO (pGO) membrane is a near-isotropic, proton-conducting GO membrane, showing a degree of anisotropy as low as 2.77 and 47% enhancement of through-plane proton conductivity as opposed to the pristine GO membrane at 25 °C and 100% relative humidity. The anisotropic behavior shows an Arrhenius relationship with temperature, while the water interlayer formation between nanosheets plays a pivotal role in the anisotropic behavior under different values of relative humidity (RH); that is, as low RH increases, water molecules tend to orient in a bimodal distribution clinching the nanosheets and forming a subnanometer, high-aspect-ratio, water interlayer, resulting in its peak anisotropy. Further increase in RH fills the interlayer gap, resulting in behaviors akin to near-isotropic, bulk water. Lastly, implementation of the pGO membrane, as the solid proton-conductive electrolyte, in an alcohol fuel cell sensor has been demonstrated, showcasing the excellent selectivity and response, exceptional linearity, and ethanol detection limits as low as 25 ppm. The amalgamation of excellent performance, high customizability, facile scalability, low cost, and environmental friendliness in the present method holds considerable potential for transforming anisotropic GO membranes into near-isotropic ion conductors to further membrane development and sensing applications.

Magnetic Field-Induced Through-Plane Alignment of the Proton Highway in a Proton Exchange Membrane

Proton exchange membranes with high through-plane proton conductivity are a critical component of high-performance fuel cells, electrolyzers, and batteries. However, isotropically distributed proto...

Correlated interfacial water transport and proton conductivity in perfluorosulfonic acid membranes.

Water must be effectively transported and is also essential for maximizing proton conductivity within fuel-cell proton-exchange membranes (PEMs). Therefore, identifying relationships between PEM properties, water transport, and proton conductivity is essential for designing optimal PEMs. Here, we use coherent Raman spectroscopy to quantify real-time, in situ diffusivities of water subspecies, bulk-like and nonbulk-like (interfacial) water, in five different perfluorosulfonic acid (PFSA) PEMs. Although the PEMs were chemically diverse, water transport within them followed the same rule: Total water diffusivity could be represented by a linear combination of the bulk-like and interfacial water diffusivities. Moreover, the diffusivity of interfacial water was consistently larger than that of bulk-like water. These measurements of microscopic transport were combined with through-plane proton conductivity measurements to reveal the correlation between interfacial water transport and proton conductivity. Our results demonstrate the importance of maximizing the diffusivity and fractional contribution of interfacial water to maximize the proton conductivity in PFSA PEMs.

Multiblock copolymers of sulfonated PSU/PPSU Poly(ether sulfone)s as solid electrolytes for proton exchange membrane fuel cells

Sulfonated multiblock copolymers composed of Polysulfone (PSU) and Polyphenylsulfone (PPSU) poly(ether sulfone) segments (SPSU/SPPSU) are synthesized for the first time by polycondensation in a “one-pot two-step synthesis” of commercial monomers, followed by sulfonation reaction with trimethylsilyl chlorosulfonate (TMSCS). Both segments are responsible for proton conductivity, although the PSU block has greater affinity to be sulfonated. Even though no microphase separation is detected, the resulting ionomers exhibit good mechanical properties due to the non-sulfonated blocks remaining and to the high molecular weights of the ionomers. The chemical structure is confirmed by 1H-NMR, 19F-NMR and FTIR analysis. The degree of sulfonation (0.93–1.58) is determined from the IEC values and 1H-NMR spectra. In situ through-plane proton conductivity measured on the MEAs is 34.1 mS cm−1 at 70 °C. A maximum power density of 400 mW cm−2, a current density of 1100 mA cm−2 and outstanding thermo-mechanical stability, these proton-conducting membranes can therefore be implemented in PEMFC.

Surface-modified fibrous membranes for fuel cell application

Low permeability layers of poly(1-vinylimidazole) were polymerised and deposited onto both sides of electrospun polyethersulfone (PES) nanofibrous sheet radiofrequency plasma. The layers not only act as an efficient fuel barrier layer but also impart high and stable proton conductivity, as well as better chemical and dimensional stabilities. Typically, the composite membrane exhibited methanol permeability as low as 33.20 x 10-8 cm2 s-1 and high through-plane proton conductivity of 52.4 mS cm-1 at 95% RH, indicating membrane selectivity of 0.675 x 108 mS.s cm-3, which is approximately 33 times greater than the selectivity of N115 under similar conditions.

Nafion/sulfonated poly(indene) polyelectrolyte membranes for fuel cell application

Abstract Sulfonated poly(indene) (SPInd), with 35% and 45% degree of sulfonation, was blended with Nafion to prepare blended membranes with 10, 15 and 20 wt.% of SPInd. Membranes were evaluated by infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. Water uptake (WU), ion exchange capacity (IEC) and through-plane proton conductivity were measured. The membranes presented similar thermal stability to Nafion. WU was slightly higher for Nafion/SPInd membranes (19-21% at RT and 40-44% at 90 °C) compared with recast Nafion (16% and 34%, respectively), and IEC values showed a similar trend. Blended Nafion membranes had increased proton conductivity of 2.41 x 10-2 and 2.37 x 10-2 Scm-1 (20 wt. % of SPInd 35% and 45%, respectively), compared with 1.16 x 10-2 Scm-1 for recast Nafion. The results show that the addition of SPInd to Nafion is a potential route towards improving the performance of Nafion in proton conductivity for use in fuel cells devices.

Infiltration of 40SiO2−40P2O5−20ZrO2 sol-gel in sSEBS membranes for PEMFCs application

This work describes the preparation of novel and low cost hybrid organic-inorganic membranes via sol-gel chemistry and direct infiltration method using a novel inorganic precursor (40SiO2−40P2O5−20ZrO2) and sulfonated styrene-ethylene-butylene-styrene triblock copolymer (sSEBS) for their use in fuel cells (PEMFC). sSEBS shows a distinct phase separated morphology which can be used as a template to incorporate the inorganic component preferentially within the ionic domains of the polymer, improving mechanical stability and reducing water uptake. The hybrid membranes are evaluated and compared to sSEBS in terms of swelling in water, IEC and FTIR. Chemical oxidation stability has been investigated using Fenton's reagent and the morphology has been observed using FE-SEM, EDX and AFM. The electrochemical characterization in single cells was carried out at 60 °C, atmospheric pressure and 100% relative humidity in order to determine hydrogen crossover, through-plane proton conductivity and cell performance. The results show that infiltration times up to 40 min lead to hybrid membranes with lower swelling in water, enhanced dimensional stability, good proton conductivity and better cell performance than pure sSEBS.